John Palmer writes about plagiarism today. I am grading senior papers, and so far I don't think I have any real examples among the eleven I've supervised this term. One suggestion I make to faculty is to have your students write papers in parts and read each part as they are produced (this makes them start the work earlier -- here's my syllabus to see what I do.) Have them write the introduction first -- you will get a good sense of the student's style. When it's time to do the theory part of the paper, you have an example to compare this to. I've told students explicitly what I am doing, and I think this probably deters them.

I don't know that this model can be generalized to term papers in, say, intermediate theory classes but only because I haven't tried it yet.